Due to current tooling limitations in casting technologies, intricate geometric details such as fine cooling passages typically cannot be cast into a component and must be formed in a subsequent machining step. Furthermore, components that must operate in high temperature environments, such as gas turbine airfoils for example, typically are formed from high temperature materials such as nickel, cobalt or iron based super alloys which have poor machineability which adds to the overall difficulty of forming the final component part.
The TOMO lithographic process is a manufacturing process for producing complex, net-shape, micro-to-meter scale structures, as described in U.S. Pat. No. 7,141,812 B2, incorporated by reference herein. The TOMO process uses a lithographic etching method to manufacture master tooling from copper or other metallic foils in extremely accurate form. The foils are produced from a 3-D digital model that is transformed into a series of cross-sectional slices of the desired 3-D solid. The foils are produced by first applying a controlled thickness coating of photo-sensitive polymer to both surfaces of the foil and then overlaying photomasks onto both surfaces of the foil. The multilayer structure is then exposed to UV light which polymerizes the exposed photosensitive polymer coating in areas not covered by the photomasks. The photomasks are then removed. The unexposed photoresist polymer is then removed chemically leaving the exposed regions of the polymer film firmly printed on the surface of the foil. The foil is then etched to remove the exposed surface, resulting in a foil print which is subsequently stacked with other foils and bonded together to form a master tool used for development of investment casting molds.